Bump org.apache.maven.plugins:maven-javadoc-plugin from 3.6.2 to 3.6.3

Bumps [org.apache.maven.plugins:maven-javadoc-plugin](https://github.com/apache/maven-javadoc-plugin) from 3.6.2 to 3.6.3.
- [Release notes](https://github.com/apache/maven-javadoc-plugin/releases)
- [Commits](apache/maven-javadoc-plugin@maven-javadoc-plugin-3.6.2...maven-javadoc-plugin-3.6.3)

---
updated-dependencies:
- dependency-name: org.apache.maven.plugins:maven-javadoc-plugin
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

pom.xml

@@ -23,7 +23,7 @@
         <rxjava.version>2.2.21</rxjava.version>
         <checkstyle.version>2.17</checkstyle.version>
         <findbugs.version>3.0.5</findbugs.version>
-        <javadoc.version>3.6.2</javadoc.version>
+        <javadoc.version>3.6.3</javadoc.version>
         <pmd.version>3.21.2</pmd.version>
         <jdepend.version>2.0</jdepend.version>
         <javancss.version>2.1</javancss.version>